A backflow prevention assembly is disclosed including a backflow prevention valve having a valve housing including a valve inlet end and a valve outlet end; a spool spacer of predetermined length having a first end and a second end; an inlet shut-off valve; and an outlet shut-off valve, wherein the spool spacer extends between the backflow prevention valve and one of the inlet shut-off valve and the outlet shut-off valve. The entire assembly, including the backflow prevention valve, the spool spacer, the inlet shut-off valve, and the outlet shut-off valve, is a certified assembly, certified by a certifying authority prior to installation. Methods of manufacturing a backflow prevention assembly and replacing a backflow prevention assembly are also disclosed.

Microscale valves for use in, e.g., micropump devices, may be formed of a slitted diaphragm bonded to the interior of a valve tube. A bump in the diaphragm and/or a backward-leakage stopper may increase the breakdown pressure of the valve. A push-rod may be used to pre-load the valve membrane to thereby increase the cracking pressure.

A backflow prevention assembly is disclosed including a backflow prevention valve having a valve housing including a valve inlet end and a valve outlet end; a spool spacer of predetermined length having a first end and a second end; an inlet shut-off valve; and an outlet shut-off valve, wherein the spool spacer extends between the backflow prevention valve and one of the inlet shut-off valve and the outlet shut-off valve. The entire assembly, including the backflow prevention valve, the spool spacer, the inlet shut-off valve, and the outlet shut-off valve, is a certified assembly, certified by a certifying authority prior to installation. Methods of manufacturing a backflow prevention assembly and replacing a backflow prevention assembly are also disclosed.

In one featured embodiment, a closure sleeve for a valve comprises a sleeve body surrounding a center axis and defined by an overall length extending from an upstream end to a downstream end. The sleeve body has an internal cavity that is enclosed at the downstream end and is open at the upstream end. The internal cavity is defined in part by a piston contact surface that is defined by an inner diameter. The piston contact surface is configured to slide against a piston to be received within the internal cavity, and a ratio of the inner diameter to the overall length is between 1.0 and 1.5.

Hydraulic valves for dampening pressure spikes and associated methods are disclosed herein. In one embodiment, a hydraulic valve for dampening pressure spikes includes: a spool configured to move axially inside the hydraulic valve; and a sleeve configured to at least partially house the spool. A location of the spool with respect to the sleeve may determine a flow of a working fluid through the hydraulic valve. A viscous damper is at least partially housed inside an opening in the spool, and a viscous friction between the viscous damper and the opening in the spool slows a motion of the spool.

A backflow prevention assembly is disclosed including a backflow prevention valve having a valve housing including a valve inlet end and a valve outlet end; a spool spacer of predetermined length having a first end and a second end; an inlet shut-off valve; and an outlet shut-off valve, wherein the spool spacer extends between the backflow prevention valve and one of the inlet shut-off valve and the outlet shut-off valve. The entire assembly, including the backflow prevention valve, the spool spacer, the inlet shut-off valve, and the outlet shut-off valve, is a certified assembly, certified by a certifying authority prior to installation. Methods of manufacturing a backflow prevention assembly and replacing a backflow prevention assembly are also disclosed.

A valve for use in a hydraulic circuit to drive a piston is fluidly connected to a first actuating chamber of the hydraulic piston. The valve is piloted to close when the first chamber is pressurized. The valve vents the fluid in the first actuating chamber when the first chamber is not pressurized. The valve permits several fluid supplies connected to the chamber via check valves to be used to drive the piston. The hydraulic piston and hydraulic circuit may be implemented in a blowout preventer operating in a subsea environment to ensure safe drilling of deepwater wells.

A backflow prevention assembly is disclosed including a backflow prevention valve having a valve housing including a valve inlet end and a valve outlet end; a spool spacer of predetermined length having a first end and a second end; an inlet shut-off valve; and an outlet shut-off valve, wherein the spool spacer extends between the backflow prevention valve and one of the inlet shut-off valve and the outlet shut-off valve. The entire assembly, including the backflow prevention valve, the spool spacer, the inlet shut-off valve, and the outlet shut-off valve, is a certified assembly, certified by a certifying authority prior to installation. Methods of manufacturing a backflow prevention assembly and replacing a backflow prevention assembly are also disclosed.

A backflow prevention assembly is disclosed including a backflow prevention valve having a valve housing including a valve inlet end and a valve outlet end; a spool spacer of predetermined length having a first end and a second end; an inlet shut-off valve; and an outlet shut-off valve, wherein the spool spacer extends between the backflow prevention valve and one of the inlet shut-off valve and the outlet shut-off valve. The entire assembly, including the backflow prevention valve, the spool spacer, the inlet shut-off valve, and the outlet shut-off valve, is a certified assembly, certified by a certifying authority prior to installation. Methods of manufacturing a backflow prevention assembly and replacing a backflow prevention assembly are also disclosed.

A valve for use in a hydraulic circuit to drive a piston is fluidly connected to a first actuating chamber of the hydraulic piston. The valve is piloted to close when the first chamber is pressurized. The valve vents the fluid in the first actuating chamber when the first chamber is not pressurized. The valve permits several fluid supplies connected to the chamber via check valves to be used to drive the piston. The hydraulic piston and hydraulic circuit may be implemented in a blowout preventer operating in a subsea environment to ensure safe drilling of deepwater wells.